More than 100,000 people in the United States annually consume the edible false morel mushroom, Gyromitra esculenta (GE). This fungus contains 11 hydrazine analogues, of which acetaldehyde methylformylhydrazone (AMFH), pentanal methylformylhydrazone (PMFH), N-methyl-N-formylhydrazine (MFH), and N-methylhydrazine (MH) were shown to be carcinogenic in mice in this laboratory. In the present grant, we have set up the carcinogenesis experiments and all have progressed well. The GE feeding induced tumors in the lungs, blood vessels, forestomachs, and cecums of mice. 3Methylbutanal N-methyl-N-formylhydrazone (3-MBMFH) and hexanal N-methyl-N-formylhydrazone (HMFH) have already induced statistically significant incidences of tumors in the lungs, preputial glands, and liver. Also, possible metabolic intermediates derived from MFH that could act as the ultimate carcinogenic species have been identified by studying the oxidative degradation of this hydrazine. Products that form under chemically oxidizing conditions have been identified, too. In this proposal, we intend to continue (1) to determine the tumor-inducing ability of the fresh GE by a lifelong feeding study in mice, (2) to study the tumorigenicity of 3-MBMFH and HMFH ingredients of the mushroom by lifelong oral administration to mice, (3) to measure chemically the amounts of AMFH, MFH, and MH in the mushroom used for the feeding experiment, and (4) to investigate the electrochemical oxidation of WH, MH, and formylhydrazine (FH) through the use of radical trapping agents. The results of the proposed study will allow us to determine the environmental significance of mushroom consumption and their toxins and reveal the mechanism of action of the three main carcinogenic hydrazines, particularly MFH (the most potent carcinogen of this series). In a recent study, a variety of tumors were induced in animals fed another fresh mushroom, the cultivated Agaricus bisporus. The proposed experiments likely will provide positive findings in a field of current interest. Virtually nothing is known about the mechanism of action of these highly carcinogenic hydrazines. Our proposed studies should identify the oxidative processes involves. No new studies are proposed. Only the completion of previously approved investigations are requested.